In the design and deployment of global communication networks, the selection of feeder cables is a core decision that directly impacts signal integrity, system cost, and long-term operational efficiency. For communication operators, regional differences in technical standards complicate this choice. This article provides a global perspective, comparing the technical characteristics, applicable international standards, and engineering applications of coaxial cable, flat feeder cable, and fiber optic cable, offering professional reference for multinational network deployment.
1. Coaxial Cable: The Cornerstone of Global RF Connectivity and its Standard Variations
1.1 Technical Principles and Performance Modeling
Coaxial cables transmit high-frequency electrical signals through a concentric structure comprising an inner conductor, dielectric, outer conductor, and sheath. Its signal attenuation (insertion loss) is a key performance metric, which can be approximated by the formula:
α ≈ (k1 * √f + k2 * f) / 100, where α is the loss (dB/100m), f is the frequency (MHz), and k1 y k2 are constants dependent on the cable structure and dielectric material [1- IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY – 2018]. This model explains why the loss of traditional coaxial cable increases drastically in 5G millimeter-wave bands, limiting its application.
1.2 Global Standard Differences and Selection Impact
International standards for coaxial cable are not uniform, requiring operators to pay attention to compatibility during multinational procurement and deployment:
- North America and parts of Asia: Widely adhere to the MIL-C-17 standard and RG series classifications (e.g., RG-6, RG-58). Although originating from the US military, the RG standards have become common references in the commercial sector.
- Europe and many international projects: Commonly adopt the IEC 61196 series international standards and DIN standards. Specifications set by the European Telecommunications Standards Institute (ETSI) often impose stricter requirements on environmental and fire safety performance (e.g., compliance with CPR regulations).
- China and specific regions: Have their own industry standards (e.g., YD/T), whose performance parameters may have subtle yet critical differences from IEC or MIL standards, particularly regarding return loss and shielding effectiveness.
Therefore, specifying a “low-loss coaxial cable” in global projects is insufficient. It is essential to clearly define the specific standard number compliant with the project location or customer requirements, such as IEC 61196-1 versus MIL-DTL-17.
2. Flat Feeder Cable: A Flexible Solution for Specific Deployment Challenges
2.1 Design Innovation and Engineering Advantages
Flat feeder cables significantly improve space utilization and wiring flexibility by compressing conductors into a flat ribbon shape. Their bend radius can be as low as a few times the cable thickness, making them highly suitable for space-constrained scenarios such as Indoor Distribution Systems (DAS), elevator shafts, and historical buildings. While their attenuation characteristics are similar to coaxial cables, the flat structure demands higher manufacturing precision to maintain stable characteristic impedance.
2.2 Global Acceptance and Standardization Status
Flat feeder cables have not yet achieved globally unified standards like their round coaxial counterparts. Their adoption heavily depends on regional engineering practices:
In North America and Europe, they are primarily used as customized or niche solutions for solving unique installation challenges. Related performance evaluations often reference general communication cable standards, such as EN 50117 (Europe) or combined with UL safety certifications.
Their core advantage lies in installation convenience, not a breakthrough in electrical performance. A study on wireless infrastructure noted that at the same frequency, high-quality flat feeder performance can rival standard coaxial cable, but its long-term mechanical reliability (e.g., performance stability after repeated bending) is a key point requiring field validation [2- International Journal of Antennas and Propagation – 2020].
3. Fiber Optic Cable: The Future-Oriented Global Backbone and 5G Fronthaul Standard
3.1 Technical Advantages and Performance Limits
Fiber optic cables guide light through the core using the principle of total internal reflection, offering immense bandwidth potential and extremely low attenuation. The attenuation coefficient of single-mode fiber can be below 0.2 dB/km in the 1550nm window. Its transmission capacity is limited by nonlinear effects (such as the Kerr effect and Raman scattering). The classical theoretical limit of its channel capacity is described by variants of the Shannon formula applied to optical fiber, with ongoing research driving new technologies like Space-Division Multiplexing [3- Journal of Lightwave Technology – 2019].
3.2 Highly Standardized Global System
Fiber optic cable is the most globally standardized feeder cable type, greatly facilitating multinational deployment:
- Core Standards: The ITU-T G.65x (Single-mode) and G.65x (Multimode) series are the absolute dominant global standards, defining the geometric, transmission, and mechanical properties of optical fibers.
- Regional Supplements: Building on this, Europe has EN 60793 (equivalent to IEC standards), and North America has the TIA-492 series. These standards are highly aligned with ITU-T on core parameters, with differences mainly in test methods or additional environmental requirements.
- 5G-Driven New Standards: To meet the stringent latency and synchronization requirements of 5G fronthaul, ITU-T G.652.D (low-loss, low-PMD fiber) and G.657.A1/B3 (bend-insensitive fiber) have become the preferred choice for global operators building new networks. The standardization work of the International Telecommunication Union (ITU) ensures interoperability between fibers from different suppliers, forming the foundation of the global supply chain.
4. Comprehensive Comparison and Global Network Selection Strategy
4.1 Three-Dimensional Comparative Analysis
| Dimensión | Coaxial Cable | Flat Feeder Cable | Fiber Optic Cable |
| Technical Performance | Limited bandwidth, loss increases significantly with frequency | Performance close to coaxial, less sensitive to bending | Nearly unlimited bandwidth, extremely low loss, immune to interference |
| Standard Globalization | Significant regional standard variations (RG, IEC, DIN, National Standards) | Lacks unified global standards, often application-specific products | Highly unified globally (ITU-T dominant) |
| Total Cost of Ownership (TCO) | Low initial cost, but high energy cost due to loss at high frequencies | Moderate initial cost, low installation cost | High initial cost, low long-term maintenance and expansion cost |
4.2 Scenario-Based Global Deployment Recommendations
- Choose Coaxial Cable: Suitable for traditional network maintenance, short-distance jumpers, or budget-constrained projects in 2G/3G/4G low-frequency bands (< 2.5 GHz). Key Action: Clarify the RF and safety standards mandatory in the project location.
- Choose Flat Feeder Cable: As a supplementary solution for special scenarios, such as indoor DAS requiring rapid deployment or with extremely narrow pathways, or temporary sites. Key Action: Require suppliers to provide full performance test reports based on IEC or EN standards, and conduct on-site reliability validation.
- Choose Fiber Optic Cable: This is the foundational choice for all new backbone networks, metropolitan area networks, 5G mid-to-high frequency band (e.g., 3.5GHz, mmWave) fronthaul networks, and any network designed for future upgrades. Key Action: Specify mainstream ITU-T fiber types (e.g., G.652.D) and ensure all connectors and patch cords comply with the IEC 61754 series standards.
Conclusion: Moving Towards a Globally Unified, Fiber-Centric Architecture
Against the backdrop of global communication networks evolving towards 5G-Advanced and 6G, feeder cable selection shows a clear trend: Fiberization is extending inexorably from the core network to the access network and even the antenna side. Although coaxial and flat feeder cables retain value in specific legacy scenarios or niche applications, the regional fragmentation of their standards increases the complexity of global operations.
For operators pursuing efficiency, future-proofing, and ease of global management, building a hybrid architecture centered on standardized fiber optic cables (complying with ITU-T G.65x/G.657 series), supplemented only where necessary at the end-user side with standardized coaxial or flat feeders, has become the most strategic choice. This not only ensures superior network performance but also minimizes the technical risks and long-term operational costs of multinational deployment by relying on a globally unified supply chain and standard system.